Different species of mites, such as house dust mites, are used to prepare allergenic extracts used in allergy formulations for use, for example, in in vivo or in vitro allergy tests, or in desensitizing preparations given to patients.
These mites include, in particular, mites of the following species: Dermatophagoides pteronyssinus, Dermatophagoides farinae, Blomia kulagini or tropicalis, Pyroglyphus africanus, and Euroglyphus maynei. 
Numerous prior art documents describe industrial relevant methods for producing mites. With respect to described improvements of the production of mites the prior art may be said to essentially focus on technical elements such as a new medium, optimal humidity, temperature, etc.
Generally speaking, for industrial relevant large scale production the prior art uses FLASKS or alternatively expressed bottles for culturing/rearing of house dust mites.
EP1236394B1 (Stallergenes corresponding to US2003/0059445A1) describes culturing of house dust mites in bottles (see example 1).
T. Batard et al (Int Arch Allergy Immunol 2006; 140:295-305) describes culturing in plastic flasks (see page 296, column 2).
F. C. Yi et al (Asian Pacific J. of Allergy and Immunology (1999) 17: 189-194) describes culturing of house dust mites in Erlenmeyer flasks (see page 190, mid column).
J. Miyamoto (Japan, J. Exp. Med. Vol, 45, 2. p. 133-138, 1975) describes culturing of house dust mites in Roux bottles (see page 134, column 2).
Culturing of house mites in Erlenmeyer flasks or Roux bottles may be considered as a “standard” procedure of the prior art. A picture of an Erlenmeyer flask is shown in FIG. 1 herein and a picture of a Roux Flask is shown in FIG. 2 herein.
For small scale house dust mite culturing/production the prior also describes use of jars (see e.g. J. Med. Ent. Vol 12, no. 6: 577-621,1976).
Also cultivation of mites in bags/envelopes has been described. Ivanov and Petrova describes in Medisinskaja Parazitoligija i Parazitarnye Bolezni, 46-49, 1985 the small scale production of Dermatophagoides phteronyssinus in closed 5×10 cm cellophane bags. According to the authors of the article the danger of mold fungi infections suppressing the mite culture is absent by cultivation of mites in cellophane bags. The amount of growth medium (1 g) and thereby the size of the mite culture that can be obtained in the cellophane bags described in the article is very low. Cellophane is also known to have a very low oxygen permeability and cellophane would therefore not be suitable as a bag material for large scale cultivation of mites.
Other species of mites are used in the field of biological control for reducing pests in crops and in greenhouses.
An article in Crop Protection, 5(2): 122-124, 1986, describes mass rearing of the predator mite Cheyletus eruditus to be used for biological control of mites in stored grain or seeds, by a method in which predator mites are cultivated in bags. Square-bottom flour bags of 1 kg capacity was filled with 100 g lettuce seeds, 20.000 prey mites and 100-200 predator mites. Each bag was closed by folding and kept at 25° C. and 75% rh for 28-35 days. To detect the correct time for termination of breeding, the ratio of predator mite to prey mite was checked every second day after day 28.
One important advantage of the cultivation method according to the invention compared to the above method of rearing predator mites is that the bags of the invention comprises a transparent area which allow visual inspection the mite growth in the bag. In general the amount of the cultivation medium used in the method of the invention is also much larger than the amount of the culture medium in the process described above.
GB 2 168 680 describes cultivation of living arthropods or similar predators in envelopes of micro perforated plastic material or paper. The bags described in this application also do not allow optimal inspection of the growth of the mites in the bags because the perforation of the plastic material may disturb inspection of mite growth.